Analog to digital converters (ADCs) are an important building block of modern electronic systems, and are the gateway between analog and digital worlds. The ideal analog to digital converter would be perfectly linear, perfectly repeatable, have zero aperture time, be noise free, convert at very high speeds, and of course consume very little power. Such ADCs are hard to find.
One of the problems involved with ADCs, linearity, has been addressed using dithering techniques. In dithering, a known analog signal is added, in the analog domain, to the signal to be digitized. This analog signal is typically generated from a digital source using a digital to analog converter (DAC) and supporting circuitry.
Introduced dither corrupts the input signal. Mathematically, if the dither signal added to the input signal is known, it can be removed from the ADC digital output, resulting in a representation of the input signal with the dither portion canceled out.
Such dithering techniques rely on the accuracy of a multiple-bit digital to analog converter (DAC) used to convert the dither signal from digital to analog form. The DAC and its supporting circuitry must be high speed, linear, noise free, and accurate. Errors in the DAC and its supporting circuitry make the dither removal process more difficult, or impossible.
What is needed is a dithering technique that eliminates the need for a multiple-bit digital to analog converter.